A calling female of Bombyx mori every several seconds lifts the abdomen to extrude pheromone glands. The amplitude of the abdominal movement changes with alternation in the flow of haemolymph due to rhythmic heartbeat reversal. The first forward beating pulse usually occurs at the lowered position of the abdomen and subsequent forward beating pulses are often inhibited by elevation of the abdomen. During a calling period in the photophase or in the early scotophase, the duration of backward beat phases is significantly longer than that of forward beat ones. When a female terminates calling behavior in the late photophase and the late scotophase, backward phases become shorter and forward phases become longer. Similar changes in length of the forward and backward beat phases occur after elimination of calling behavior by mating and by transection of the ventral nerve cord. These observations suggest peripheral modulation of heartbeat reversal rhythm. The longer duration of the backward beat phases may be suitable to maintain the calling posture and for efficient transport of metabolites and tracheal ventilation in the abdomen with a high rate of metabolism during calling behavior.